TMFF: Trustworthy Multi-Focus Fusion Framework for Multi-Label Sewer Defect Classification in Sewer Inspection Videos

Chuanfei Hu, Chenyang Zhao, Hang Shao, Jin Deng, Yongxiong Wang

Abstract: An automatic vision-based sewer inspection plays a vital role of sewage system in a modern city. Recent advances focus on modeling a deep learning-based method to realize the sewer inspection system, benefiting from the capability of data-driven feature extraction. Although the acceptable performances of sewer defect classification are achieved, there is still a gap between the emerged methods and actual application scenarios. The first issue is that the multi-focus complementarity is ignored to represent the sewer defect, resulting in capturing the multi-scale information of sewer defect inefficiently. Second, the inherent uncertainty of sewer defect is not considered, while the serious unknown sewer defect categories would be missed, resulting in the untrustworthy sewer inspection. In this paper, we focus on quick-view (QV)-based sewer inspection, while a trustworthy multi-focus fusion framework (TMFF) is proposed, jointly combining multi-label classification and uncertainty estimation. Specifically, focal segment module (FSM) is designed based on optical flow to split the QV sewer video into long-focus and short-focus segments, where the multi-focus segments can be modeled to represent the multi-scale information of sewer defect. Then, evidential deep learning (EDL) is introduced to quantify the uncertainty, while joint expert scheme (JES) is designed to aggregate the expert opinions of multi-focus segments. Moreover, evidential disambiguating strategy (EDS) is proposed to alleviate the ambiguity of uncertainty estimation. Extensive experiments are conducted on VideoPipe, in which the superiority of TMFF is demonstrated compared with the state-of-the-art methods. Furthermore, we validate the potential capability of TMFF against the unknown cases of sewer defects.